Procter & Gamble on Thursday said activist investor Nelson Peltz's plan to boost shareholder value would result in higher costs, lower profits and another restructuring that could lead to a breakup of the company.

Peltz's Trian Partners released its long-awaited proposal on Wednesday, and called for P&G to be organized into "three largely autonomous business units under a lean holding company".

P&G said it had studied several organizational structures, including the one proposed by Peltz, and concluded it would result in higher costs, lower efficiency, reduced profits, and an added layer of management complexity.

Trian, P&G's fifth-largest shareholder, has been locked in a prolonged battle with the consumer products conglomerate, raising investor hopes of a break-up of the company.

P&G's shares, which have risen 5.5 percent since Peltz announced his stake in the company in February, were slightly higher before the opening bell.